NUCLEAR-MAGNETIC-RESONANCE OF MOLECULAR-BEAM EPITAXIALLY GROWN CO-CU SUPERLATTICES THAT EXHIBIT LARGE MAGNETORESISTANCE

The Co-59 NMR has been measured for superlattices of Co(15 angstrom)/Cu (7 or 18 angstrom) grown with either a Au or Cu buffer layer between the substrate and the superlattice. As was reported earlier the Co (15 angstrom)/Cu (7 angstrom) (Au) superlattice has the largest magnetoresistance (DELTAR/R approximately 26%) known for a MBE grown Co/Cu multilayer. The NMR measurements show that the Au-based superlattices have very flat interfaces and (111) orientation, two features which were supposed to preclude a large value of DELTAR/R, and that the average strain in the Co layers is greater for a Au than a Cu buffer layer.